A variety of medical devices for medicament delivery are known. Such devices may be categorized according to how administration of a medicament is controlled: self-administered by the patient, by machine control programmed by a care provider, or by some combination—for example, administered by machine upon demand by a patient, in some cases subject to limits established by a care provider. Such administration by patient demand may be provided by so-called patient-controlled analgesia, or “PCA,” systems. In the context of this disclosure, PCA may also refer to patient-controlled administration of non-analgesic medication delivery.
PCA infusion pumps have demonstrated their usefulness over a number of years. PCA pumps are typically designed to permit a patient to safely self-medicate with pain medications. Under the care of a healthcare practitioner, a patient using a PCA pump may receive a dose of medication by activating a control on or connected to the pump such as a push-button dose request switch. Such activation on demand by the patient may start a pumping mechanism in the PCA pump that delivers, for example, a measured dose of a fluidic drug (e.g., a liquid narcotic medication) to the patient via an intravenous or other fluid line within an allowable time interval. If a PCA command is activated during a time interval in which an allowable dose has already been administered, the delivery of a subsequent dose may be “locked out” until an appropriate time interval has passed, thereby safely preventing the patient from taking more than a maximum allowable dose of medication during a time interval. PCA pumps may provide other safety features to patients individually or in various combinations, such as, for example, enforcing maximum numbers of self-administered doses over programmable time periods and enforcing maximum amounts of medicaments delivered over programmable time periods. PCA pumps may also provide other functions, such as recording and reporting the volume of the medicament delivered over selected time intervals.
Recently, additional modes of patient-controlled medication delivery have been proposed or made available. For example, WO 2013/158712, “Medication Dispensers,” describes a medication dispenser configured for dispensing substantially solid medication in response to activation of a medication dose request device. Solid medication PCA dispensers may share some characteristics with PCA infusion pumps, but may also present new challenges for medication management.
In view of the increasing prevalence of patient controlled analgesia, as well as the increasing diversity of on-demand medication dispensing or delivery systems, there is a need to improve PCA systems to result in appropriate delivery of medications to patients.